A new type of display panel having memory is described in U.S. Pat. No. 4,386,348, dated May 31, 1983, of George E. Holz and James A. Ogle. The panel comprises a gas-filled envelope including a layer of D.C. scan/address cells and a layer of quasi A.C. display cells. The scan cells are arrayed in rows and columns, and the display cells are arrayed in corresponding rows and columns. The scan cells are scanned and turned on column-by-column by operation of their electrodes while sustain signals are simultaneously being applied to the display cells, and the same electrodes are used to transfer information from selected scan cells to the associated display cells where glow is sustained by the sustainer signals. The cells which are energized in the entire panel, by this routine, display a stationary but changeable message.
In one mode of operation of these panels described and claimed in an application Ser. No. 525,282 entitled SYSTEM AND METHOD FOR OPERATING A DISPLAY PANEL HAVING MEMORY, filed concurrently herewith by George E. Holz and James A. Ogle, the panel is operated and displays a message. Then, at some time, it is, in effect, turned off while information which is in the panel is erased or while new information is written into the panel, and then it is turned on again to display the new information. If the panel is held off for too long a time before it is turned on again, it may not come back on properly and some information may be lost. The present invention solves this problem, and it also permits turning off a panel having a message contained in it and then turning on the panel minutes later without losing the message. Thus, whenever cell re-ignition is required, the present invention can be employed.